Oxidation Behavior of Thermally Grown Oxide on Aluminized Coating Irradiated by High-Current Pulsed Electron Beam

The oxidation of CoCrAlY coatings, which are prepared by atmospheric plasma spray, additionally aluminized by electric beam vacuum deposition, and finally modified by high-current pulsed electron beam irradiation, is investigated. Meanwhile, the isothermal oxidation performance of untreated coating at 1050 °C is compared to the modified coating. The surface microstructure, cross-sectional microstructure, and phase transformation of the coatings are characterized by means of scanning electron microscope and energy-dispersive spectrometry (EDS). Results reveal that the thermally grown oxide (TGO) in untreated coatings is composed of two distinct layers: a large amount of mixed gray oxides in the outer layer and a thin Al 2 O 3 film in the inner layer. In comparison, modified coatings exhibit single TGO layer and homogeneous TGO composition. The EDS line scanning result shows that TGO is primarily comprised of α-Al 2 O 3 . These results display that the modified coatings have a much higher oxidation resistance.